JP4310834B2 - Method for producing alumina powder for sintered body - Google Patents
Method for producing alumina powder for sintered body Download PDFInfo
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- JP4310834B2 JP4310834B2 JP05031699A JP5031699A JP4310834B2 JP 4310834 B2 JP4310834 B2 JP 4310834B2 JP 05031699 A JP05031699 A JP 05031699A JP 5031699 A JP5031699 A JP 5031699A JP 4310834 B2 JP4310834 B2 JP 4310834B2
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- alumina
- alumina powder
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Description
【０００１】
【発明の属する技術分野】
本発明は焼結体用アルミナ粉末の製造方法に関する。詳細には、粗粒が少なく、かつ高い成形密度を有する成形体を提供し得る焼結体用アルミナ粉末の製造方法に関する。
【０００２】
【従来の技術】
従来より、アルミナ粉末は耐熱性、耐食性、耐摩耗性、電気絶縁性、機械的強度等の物性に優れていることにより、ＩＣ基板、透光管、軸受、切削工具又はＮａＳ電池用電解質等の焼結体原料、フロッピーディスク又は磁気テープ等への充填材として使用されている。
【０００３】
従来より、焼結体原料としてのアルミナ粉末は粗粒が少なく、かつ成形時の成形密度が高いものが良いとされている。しかして、該アルミナ粉末としては、商業的観点から、通常、バイヤー法により得られた原料アルミナを転動ボールミルや振動ボールミル等粉砕装置によって粉砕、或いは凝集粒を解砕したものが用いられている。
【０００４】
しかしながら、前記粉砕装置を用いる方法では粉砕に供する原料アルミナ及び粉砕条件を最適化することによって、ある程度の成形密度を有するアルミナ粉末が得られるものの、粗粒が少なく、かつ成形密度が高いアルミナ粉末を得ることは困難であった。
【０００５】
【発明が解決しようとする課題】
かかる事情下に鑑み、本発明者等はバイヤー法等で得られる原料アルミナから粗粒が少なく、かつ高い成形密度を有する成形体を提供し得る焼結体用アルミナ粉末を得るべく鋭意検討を進めた結果、特定の粒子径、比表面積を有する原料アルミナを粉砕した後、特定の粉砕機を用いて処理する場合には上記課題を解決し得ることを見出し本発明を完成するに至った。
【０００６】
【課題を解決するための手段】
即ち、本発明は、平均二次粒子径が３０μｍ〜１５０μｍであり、ＢＥＴ比表面積が２ｍ２／ｇ以下であり、ブレーン比表面積が９５００ｃｍ２／ｇ以下である原料アルミナを転動ボールミルで粉砕した後、気流式粉砕機を用いて処理することを特徴とする焼結体用アルミナ粉末の製造方法を提供するにある。
【０００７】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明に用いる原料アルミナは、平均二次粒子径が３０μｍ〜１５０μｍ、好ましくは４０μｍ〜１００μｍであり、ＢＥＴ比表面積が２ｍ2／ｇ以下、好ましくは０．４ｍ2／ｇ〜１．８ｍ2／ｇであり、ブレーン比表面積が９５００ｃｍ2／ｇ以下、好ましくは５０００ｃｍ2／ｇ〜９０００ｃｍ2／ｇの範囲である。該原料アルミナの平均粒子径が上記範囲を外れる場合には、高い成形密度を有するアルミナ粉末を得ることが困難である。該原料アルミナのＢＥＴ比表面積が２ｍ2／ｇより高い場合には、たとえ原料アルミナを粉砕した後、気流式粉砕機を用いて処理したとしても、粗粒の少なく、かつ高い成形密度を有するアルミナ粉末を得ることは困難である。ブレーン比表面積が９５００ｃｍ2／ｇより大きい場合には、高い成形密度を有するアルミナ粉末を得ることは困難である。また、粉砕後のアルミナ粉末の粒度分布は、アルミナを構成する一次粒子の粒度分布に起因するため、該原料アルミナは、通常、平均一次粒子径が０．８μｍ〜４μｍ、好ましくは１μｍ〜２μｍであるものを用いることが推奨される。本発明に用いる原料アルミナの製造方法としては、例えば、アルミン酸ナトリウム溶液から晶析により得られた水酸化アルミニウム（ギブサイト）をロータリーキルン、トンネルキルン等を用いて焼成する方法（以下、バイヤー法と称する。）が挙げられる。
【０００８】
本発明は上記物性を有する原料アルミナを粉砕することを特徴とする。
【０００９】
前記粉砕は、例えばローラーミル、高速回転粉砕機、転動ボールミル、振動ボールミル、遊星ミル、攪拌ミル等（化学工学便覧 改定五版、第８２８〜８３４頁、丸善株式会社昭和６３年３月１８日発行）が挙げられ、就中、転動ボールミルの適用が推奨される。尚、粉砕装置は回分式、連続式何れの方式であってもよい。また、前記粉砕は、通常、原料アルミナをその平均二次粒子径が約１／５以下、好ましくは１／８以下になる迄行うことが好ましい。平均二次粒子径が１／５以下になる迄粉砕することにより、より高い成形密度を有するアルミナ粉末を得ることが可能である。
【００１０】
前記粉砕を行うに際しては、例えば転動ボールミルを用いて粉砕媒体１００重量部に対して原料アルミナ約１０重量部〜３０重量部を供給し、その平均二次粒子径が約１／５以下になる迄粉砕する方法が挙げられる。また、粉砕媒体は製品汚染を防止できることから、Ａｌ2Ｏ3純度９０％以上のアルミナ質球形媒体が好ましい。
【００１１】
本発明は、次いで、粉砕して得られたアルミナを気流式粉砕機を用いて処理することを特徴とする。
【００１２】
本発明に用いる気流式粉砕機としては、例えば、気流衝撃式粉砕機（気流によって粒子同士を衝突させて粉砕する装置）、気流衝突板式粉砕機（気流によって衝突板に粒子を衝突させて粉砕する装置）または対向気流式粉砕機等が挙げられる。粗粒を低減できることから気流衝撃式粉砕機の適用が推奨される。特に、粗粒の低減効果が高いことから分級機能が組み込まれている型式の気流式粉砕機の適用が推奨される。尚、気流式粉砕機に変えて転動ボールミルや振動ボールミル等を用いて処理する場合には本発明の効果は得られない。
【００１３】
処理条件は、気流式粉砕機の機種によって異なり一義的ではないが、通常、粉砕空気圧力が約４ｋｇ／ｃｍ2以上、好ましくは約５ｋｇ／ｃｍ2〜約８ｋｇ／ｃｍ2である。また、アルミナ粉末は一般に研磨材として用いられているように高速で流動している場合には、粉砕機内面にある程度の摩耗が発生するので摩耗を受けやすい箇所、例えばノズル等の部分は耐摩耗性の高い材料、例えばアルミナ、炭化珪素等を用いることが望ましい。
【００１４】
本発明の製造方法を行うに際しては、通常、平均二次粒子径が約３０μｍ〜約１００μｍであり、ＢＥＴ比表面積が約２ｍ2／ｇ以下であり、ブレーン比表面積が９５００ｃｍ2／ｇ以下であるバイヤー法により得られた原料アルミナを粉砕した後、粉砕空気圧力４ｋｇ／ｃｍ2以上の条件で気流式粉砕機を用いて処理し、該気流式粉砕機から排出されたアルミナ粉末をサイクロンおよび／またはバグフィルター等によって捕集、回収すればよい。また、粉砕時又は気流式粉砕機を用いる処理時に必要に応じてエチレングリコール、ステアリン酸等の助剤、シランカップリング剤等の表面処理剤を添加してもよい。
【００１５】
本発明により得られた焼結体用アルミナ粉末は、通常、平均二次粒子径が約０．８μｍ〜約４μｍ、好ましくは約１μｍ〜約２μｍであり、＋５μｍ量が約１％以下、好ましくは０．５％以下であり、成形密度は２．２０ｇ／ｃｍ3以上であり、高密度焼結体又は高強度焼結体を提供し得るものである。また、前記焼結体用アルミナ粉末はＩＣ基板、透光管、軸受、切削工具及びＮａＳ電池用電解質等の焼結体原料として好適に用いることができることは勿論、フロッピーディスク及び磁気テープ等への充填材、研磨材または耐火物等に用いることができるものである。
【００１６】
【実施例】
以下、本発明を実施例により更に詳細に説明するが、本発明は実施例により制限を受けるものではない。尚、原料アルミナ及びアルミナ粉末の物性測定は以下の方法で行った。
【００１７】
原料アルミナの物性測定
平均一次粒子径（μｍ）： 顕微鏡写真により１００個のアルミナについて、各々の一次粒子径を測定し、これらの平均より求めた。
平均二次粒子径（μｍ）： 篩別法により測定した。
ＢＥＴ比表面積（ｍ2／ｇ）： 窒素吸着法により測定した。
ブレーン比表面積（ｃｍ2／ｇ）： ブレーン比表面積測定装置ＳＳ−１００（島津製作所製）を用い、恒圧空気式測定方法により測定した。
【００１８】
アルミナ粉末の物性測定
平均二次粒子径（μｍ）： レーザー散乱式粒度分布計〔リード アンド ノースラップ（ＬＥＥＤ＆ＮＯＲＴＨＲＵＰ）社製マイクロトラック〕により、５０重量％径を測定した。
成形密度（ｇ／ｃｍ3）： 冷間静水圧成形機（成形圧：５００ｋｇ／ｃｍ2）を用いて成形した後、得られた成形体の密度を水銀アルキメデス法により測定した。
【００１９】
実施例１
バッチ式転動ボールミル（粉砕媒体：２５ｍｍφの純度９３％アルミナボール、回転数：３６ｒｐｍ）に、前記粉砕媒体１００重量部に対して平均二次粒子径４５μｍ、平均一次粒子径１．５μｍ、ＢＥＴ比表面積１．３ｍ2／ｇ、ブレーン比表面積８０００ｃｍ2／ｇのバイヤー法により得られた原料アルミナ１１重量部を入れて粉砕し、平均二次粒子径１．７μｍのアルミナを得た。次いで得られたアルミナを気流衝撃式粉砕機ＰＪＭ−２８０ＳＰ型（商品名、日本ニューマチック製、フィード量：３０ｋｇ／ｈｒ、粉砕空気圧力：５ｋｇ／ｃｍ2の条件で）を用いて処理し、前記粉砕機から排出されたアルミナ粉末をサイクロンによって捕集、回収し、アルミナ粉末Ａを得た。得られたアルミナ粉末Ａの物性を第１表に示す。
【００２０】
比較例１
実施例１で用いたと同じ原料アルミナをフィード量３０ｋｇ／ｈｒ、粉砕空気圧力５ｋｇ／ｃｍ2の条件で気流衝撃式粉砕機（商品名：ＰＪＭ−２８０ＳＰ型、日本ニューマチック製）を用いて粉砕し、該粉砕機から排出されたアルミナ粉末をサイクロンによって捕集、回収し、アルミナ粉末Ｂを得た。得られたアルミナ粉末Ｂの物性を第１表に示す。
【００２１】
比較例２
バッチ式転動ボールミル（粉砕媒体：２５ｍｍφの純度９３％アルミナボール、回転数：３６ｒｐｍ）に、前記粉砕媒体１００重量部に対して実施例１で用いたと同じ原料アルミナ１１重量部を入れて粉砕し、平均二次粒子径１．７μｍのアルミナ粉末Ｃを得た。得られたアルミナ粉末Ｃの物性を第１表に示す。
【表１】
【発明の効果】
以上詳述した如く、本発明はバイヤー法により得られた原料アルミナ等から、粗粒が少なく、かつ高い成形密度を有する成形体を提供し得るアルミナ粉末の製造方法を提供するものであり、その工業的価値は大なるものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an alumina powder for a sintered body. More specifically, the present invention relates to a method for producing an alumina powder for a sintered body that can provide a molded body with few coarse particles and a high molding density.
[0002]
[Prior art]
Conventionally, alumina powder has excellent physical properties such as heat resistance, corrosion resistance, wear resistance, electrical insulation, mechanical strength, etc., so that it can be used for IC substrates, light-transmitting tubes, bearings, cutting tools, NaS battery electrolytes, etc. It is used as a filler for sintered compacts, floppy disks, magnetic tapes and the like.
[0003]
Conventionally, alumina powder as a sintered body raw material is good in that it has few coarse particles and has a high molding density during molding. Thus, as the alumina powder, from a commercial viewpoint, the raw material alumina obtained by the Bayer method is usually pulverized by a pulverizing apparatus such as a rolling ball mill or a vibration ball mill, or the agglomerated grains are crushed. .
[0004]
However, in the method using the pulverizer, alumina powder having a certain molding density can be obtained by optimizing the raw material alumina to be pulverized and the pulverization conditions. It was difficult to get.
[0005]
[Problems to be solved by the invention]
In view of such circumstances, the present inventors proceeded diligently to obtain an alumina powder for a sintered body that can provide a molded body having a small number of coarse particles and a high molding density from raw material alumina obtained by the Bayer method. As a result, it was found that the above problems can be solved when the raw material alumina having a specific particle diameter and specific surface area is pulverized and then processed using a specific pulverizer, and the present invention has been completed.
[0006]
[Means for Solving the Problems]
That is, in the present invention, raw material alumina having an average secondary particle diameter of 30 μm to 150 μm, a BET specific surface area of 2 m 2 / g or less, and a brane specific surface area of 9500 cm 2 / g or less was pulverized by a rolling ball mill . Then, it is providing the manufacturing method of the alumina powder for sintered compacts characterized by processing using an airflow-type grinder.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
Alumina raw material used in the present invention have an average secondary particle size 30Myuemu～150myuemu, preferably 40 m to 100 m, BET specific surface area of 2m 2 / g or less, preferably 0.4m 2 /g~1.8m 2 / g, the Blaine specific surface area of 9500cm 2 / g or less, preferably in the range of 5000cm 2 / g~9000cm 2 / g. When the average particle diameter of the raw material alumina is out of the above range, it is difficult to obtain an alumina powder having a high molding density. When the BET specific surface area of the raw material alumina is higher than 2 m 2 / g, even if the raw material alumina is pulverized and then processed using an airflow type pulverizer, it has few coarse particles and has a high molding density. It is difficult to obtain a powder. When the Blaine specific surface area is larger than 9500 cm 2 / g, it is difficult to obtain an alumina powder having a high molding density. Further, since the particle size distribution of the pulverized alumina powder is caused by the particle size distribution of the primary particles constituting the alumina, the raw material alumina usually has an average primary particle size of 0.8 μm to 4 μm, preferably 1 μm to 2 μm. It is recommended to use some. As a method for producing raw material alumina used in the present invention, for example, a method of firing aluminum hydroxide (gibbsite) obtained by crystallization from a sodium aluminate solution using a rotary kiln, tunnel kiln or the like (hereinafter referred to as a buyer method). .).
[0008]
The present invention is characterized in that the raw material alumina having the above physical properties is pulverized.
[0009]
The pulverization may be performed by, for example, a roller mill, a high-speed rotary pulverizer, a rolling ball mill, a vibrating ball mill, a planetary mill, a stirring mill, etc. (Chemical Engineering Handbook 5th revised edition, pages 828-834, Maruzen Co., Ltd. March 18, 1988) In particular, the application of a rolling ball mill is recommended. The pulverizer may be either a batch type or a continuous type. The pulverization is usually preferably carried out until the average secondary particle diameter of the raw material alumina is about 1/5 or less, preferably 1/8 or less. By pulverizing until the average secondary particle diameter becomes 1/5 or less, it is possible to obtain an alumina powder having a higher molding density.
[0010]
When performing the pulverization, for example, using a rolling ball mill, about 10 to 30 parts by weight of the raw material alumina is supplied to 100 parts by weight of the pulverization medium, and the average secondary particle size becomes about 1/5 or less. The method which grind | pulverizes until is mentioned. Further, since the grinding medium can prevent product contamination, an alumina spherical medium having an Al 2 O 3 purity of 90% or more is preferable.
[0011]
Next, the present invention is characterized in that the alumina obtained by pulverization is treated using an airflow pulverizer.
[0012]
Examples of the airflow type pulverizer used in the present invention include an airflow impact type pulverizer (an apparatus that pulverizes particles by colliding with airflow), an airflow collision plate type pulverizer (the particles collide with the collision plate by an airflow and pulverize). Apparatus) or an opposed air flow type pulverizer. The application of an airflow impact pulverizer is recommended because coarse particles can be reduced. In particular, it is recommended to use a type of airflow type pulverizer having a classification function because of its high effect of reducing coarse particles. It should be noted that the effect of the present invention cannot be obtained when processing is performed using a rolling ball mill, a vibrating ball mill or the like instead of the airflow type pulverizer.
[0013]
The treatment conditions differ depending on the model of the airflow type pulverizer and are not unambiguous, but usually the pulverization air pressure is about 4 kg / cm 2 or more, preferably about 5 kg / cm 2 to about 8 kg / cm 2 . In addition, when alumina powder is flowing at a high speed as is generally used as an abrasive, a certain amount of wear occurs on the inner surface of the pulverizer. It is desirable to use a high-performance material such as alumina or silicon carbide.
[0014]
In carrying out the production method of the present invention, the average secondary particle diameter is usually about 30 μm to about 100 μm, the BET specific surface area is about 2 m 2 / g or less, and the brane specific surface area is 9500 cm 2 / g or less. After the raw material alumina obtained by the Bayer method is pulverized, it is treated with an airflow pulverizer under a pulverization air pressure of 4 kg / cm 2 or more, and the alumina powder discharged from the airflow pulverizer is treated with a cyclone and / or Collect and collect with a bag filter or the like. Moreover, you may add surface treatment agents, such as auxiliary agents, such as ethylene glycol and a stearic acid, and a silane coupling agent at the time of a grinding | pulverization or the process which uses an airflow-type grinder.
[0015]
The alumina powder for sintered bodies obtained by the present invention usually has an average secondary particle size of about 0.8 μm to about 4 μm, preferably about 1 μm to about 2 μm, and an amount of +5 μm is about 1% or less, preferably The molding density is 2.20 g / cm 3 or more, and can provide a high-density sintered body or a high-strength sintered body. In addition, the alumina powder for a sintered body can be suitably used as a raw material for a sintered body such as an IC substrate, a light-transmitting tube, a bearing, a cutting tool, and an electrolyte for a NaS battery. It can be used as a filler, abrasive or refractory.
[0016]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited by an Example. The physical properties of the raw material alumina and the alumina powder were measured by the following method.
[0017]
Measurement of primary physical properties of raw material alumina Average primary particle diameter (μm): The primary particle diameter of each of 100 aluminas was measured by a micrograph and obtained from the average.
Average secondary particle diameter (μm): measured by a sieving method.
BET specific surface area (m 2 / g): Measured by nitrogen adsorption method.
Blaine specific surface area (cm 2 / g): Measured by a constant pressure pneumatic measurement method using a Blaine specific surface area measuring device SS-100 (manufactured by Shimadzu Corporation).
[0018]
Measurement of physical properties of alumina powder Average secondary particle diameter (μm): A 50 wt% diameter was measured with a laser scattering type particle size distribution meter (Microtrac manufactured by LEED & NORTHUP).
Molding density (g / cm 3 ): After molding using a cold isostatic press (molding pressure: 500 kg / cm 2 ), the density of the obtained molded body was measured by the mercury Archimedes method.
[0019]
Example 1
In a batch type rolling ball mill (grinding medium: 93% alumina ball of 25 mmφ, rotation speed: 36 rpm), the average secondary particle diameter is 45 μm, the average primary particle diameter is 1.5 μm, and the BET ratio is 100 parts by weight of the grinding medium. 11 parts by weight of raw material alumina obtained by the Bayer method having a surface area of 1.3 m 2 / g and a Blaine specific surface area of 8000 cm 2 / g was added and pulverized to obtain alumina having an average secondary particle size of 1.7 μm. Next, the obtained alumina was treated using an air-flow impact pulverizer PJM-280SP type (trade name, manufactured by Nippon Pneumatic, feed amount: 30 kg / hr, pulverization air pressure: 5 kg / cm 2 ), The alumina powder discharged from the pulverizer was collected and collected by a cyclone to obtain alumina powder A. Table 1 shows the physical properties of the obtained alumina powder A.
[0020]
Comparative Example 1
The same raw material alumina as used in Example 1 was pulverized using an airflow impact pulverizer (trade name: PJM-280SP type, manufactured by Nippon Pneumatic Co., Ltd.) under the conditions of a feed amount of 30 kg / hr and a pulverization air pressure of 5 kg / cm 2. The alumina powder discharged from the pulverizer was collected and collected by a cyclone to obtain alumina powder B. The physical properties of the obtained alumina powder B are shown in Table 1.
[0021]
Comparative Example 2
11 parts by weight of the same raw material alumina as used in Example 1 was added to 100 parts by weight of the grinding medium in a batch type rolling ball mill (grinding medium: 93% alumina ball of 25 mmφ, rotation speed: 36 rpm) and pulverized. Alumina powder C having an average secondary particle diameter of 1.7 μm was obtained. The physical properties of the obtained alumina powder C are shown in Table 1.
[Table 1]
【The invention's effect】
As described above in detail, the present invention provides a method for producing an alumina powder that can provide a molded body having a small number of coarse particles and a high molding density from raw material alumina obtained by the Bayer method. Industrial value is great.
Claims (2)
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| Application Number | Priority Date | Filing Date | Title |
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| JP05031699A JP4310834B2 (en) | 1999-02-26 | 1999-02-26 | Method for producing alumina powder for sintered body |
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| Application Number | Priority Date | Filing Date | Title |
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| JP05031699A JP4310834B2 (en) | 1999-02-26 | 1999-02-26 | Method for producing alumina powder for sintered body |
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| JP2000247751A JP2000247751A (en) | 2000-09-12 |
| JP4310834B2 true JP4310834B2 (en) | 2009-08-12 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111995378A (en) * | 2020-08-27 | 2020-11-27 | 建德华明高纳新材料有限公司 | Low-water-content alumina for lithium battery ceramic diaphragm and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4514894B2 (en) * | 2000-04-28 | 2010-07-28 | 昭和電工株式会社 | Aluminum oxide powder with excellent fillability and process for producing the same |
| JP2003176127A (en) * | 2001-08-08 | 2003-06-24 | Showa Denko Kk | alpha-ALUMINA FOR CORDIERITE CERAMIC, METHOD OF PRODUCING THE SAME, AND STRUCTURE OF CORDIERITE CERAMIC USING THE alpha-ALUMINA |
| JP4270848B2 (en) * | 2002-11-08 | 2009-06-03 | 昭和電工株式会社 | Alumina particles and method for producing the same |
| JP5065728B2 (en) * | 2007-03-28 | 2012-11-07 | 株式会社ブリヂストン | Crusher |
| CN103237604B (en) * | 2011-02-28 | 2015-07-22 | 日清工程株式会社 | Method for grinding powder |
| JPWO2012124452A1 (en) * | 2011-03-16 | 2014-07-17 | 株式会社日清製粉グループ本社 | Powder manufacturing method |
| JP6811936B2 (en) * | 2016-11-02 | 2021-01-13 | 日本電気硝子株式会社 | Manufacturing method of aluminosilicate glass |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111995378A (en) * | 2020-08-27 | 2020-11-27 | 建德华明高纳新材料有限公司 | Low-water-content alumina for lithium battery ceramic diaphragm and preparation method thereof |
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